On the anomalous pinning properties of the C15 Laves phase superconductor CeRu₂

We report the anomalous field (H) dependence of pinning force density F_P as deduced from our magnetization measurements on the single-crystal and polycrystalline samples of CeRu₂. It is shown that, contrary to a single maximum in other hard type II superconductors, CeRu₂ samples exhibit two distinct peak features in their F_P-H plots. Our results show that the scaling of F_P with the applied magnetic field at different temperatures cannot be described by the conventional Kramer model based on crossover from a line-breaking regime to a flux-line lattice shearing regime.